Find out what Metrohm has to offer for the monitoring of the water chemistry in thermal power plants, the wet chemical processing of solar cells and battery electrolytes, or electrochemical measurements of energy storage devices.

Taking high-precision Metrohm ion chromatography to an even higher level of autonomy, the Process IC can connect up to 20 sample streams and provide reliable multicomponent results for superior process control.

Sample preparation for VA: UV digestion

Voltammetry, being highly specific, can deal with high salt loads.

Organic contamination of a sample, however, can interfere with the VA trace analysis of heavy metals. The 909 UV Digester quickly and effectively breaks down organic molecules by UV photolysis, thereby enabling reliable determinations.

Key features

Suitable for transparent samples with low to medium organic contamination

Fully automatic simultaneous processing of up to 12 samples at a time

Low risk of sample contamination due to minute amounts of required reagents

UV digestion: How it works

After a small amount of H2O2 has been added to the sample as radical initiator, the sample is irradiated with UV light with wavelengths of 200 to 400 nm, producing OH radicals that spontaneously react with the organic molecules.

In the resulting radical chain reaction, all the organic molecules are broken down to low-molecular-weight compounds such as CO2, H2O, N2, or NH3, which do not interfere with VA analysis.

Effective sample preparation – recommended by standards

For transparent samples that exhibit low to medium organic contamination, i.e., carbon concentrations up to approximately 100 mg/L, UV digestion is the method of choice. Standards recommending sample preparation by UV photolysis include the following:

Fully automatic digestion

Up to 12 samples, arranged concentrically around the UV lamp to achieve uniform irradiation, can be treated at a time.

Photolysis under controlled conditions

After the user has entered the digestion temperature and time, the 909 UV Digester makes sure that these are maintained: a Pt1000 temperature sensor measures the digestion temperature in a reference sample while an integral microprocessor controls the digestion temperature and the digestion time.

No sample evaporation or losses of volatile analytes

This also means that the 909 UV Digester can be used for sample preparation when analyzing samples containing mercury, arsenic, or selenium which are volatile at elevated temperatures or readily form volatile compounds.

Low-maintenance air cooling

The UV lamp that is at the heart of the 909 UV Digester generates heat; this is dissipated by a fan located in the base of the instrument. This air cooling has the advantage that no cooling water supply is needed.

Easy and safe operation

The 909 UV Digester integrates in one housing the wet section and the control unit.

The latter serves the operation of the instrument and, via a display, provides information on the ongoing digestion. Users operating the instrument are protected from harmful UV radiation by a shield mounted on it.